JP2022097806A - Adhesive, adhesive sheet and optical adhesive sheet - Google Patents

Abstract

To provide an adhesive sheet which can satisfy high adhesion and heat resistance that are required qualities necessary for a splash prevention film even when the sheet is thin, is required for a housing glass film, and is also excellent in dent resistance.SOLUTION: An adhesive composition contains an acrylic copolymer (A), an epoxy resin (B) and a curing agent (C), in which the acrylic copolymer (A) is a copolymer of a monomer mixture containing monomers (a-1) to (a-3), contains 10-50 mass% of the monomer (a-1), 40-80 mass% of the monomer (a-2) and 5-10 mass% of the monomer (a-3) in 100 mass% of the monomer mixture, and the epoxy resin (B) is a bisphenol type epoxy resin having a weight average molecular weight (Mw) of 200-1,000.SELECTED DRAWING: None

Description

The present invention relates to a pressure-sensitive adhesive containing an acrylic copolymer, a pressure-sensitive adhesive sheet, and an optical pressure-sensitive adhesive sheet.

In recent years, display devices such as smart devices and car navigation systems that use an image display device such as a liquid crystal display or an organic EL display in combination with a touch panel have become widespread. These touch panel-integrated display devices are provided with a cover panel on the front surface in order to protect the module. Further, in order to prevent the glass from scattering when the cover glass is damaged, a shatterproof film having an adhesive layer (hereinafter, also referred to as “cover glass film”) is used.

Smartphones and tablets are composed of a cover glass / module / housing that serves as a support. In the past, aluminum was used as the housing material, and it was composed of a cover glass / module / aluminum housing, but in recent years, glass has been used as the housing material for the purpose of improving communication speed and design. It is becoming like that. In the display device of the glass housing, a shatterproof film having an adhesive layer not only on the cover glass but also on the inner surface of the glass housing (between the module and the glass housing) (hereinafter, "film for housing glass"). ) Is used.

The shatterproof film needs to have the ability to protect the glass from external impact. The adhesive used for the shatterproof film has high adhesiveness and impact resistance (for example, adhesive strength to glass) that does not peel off from the cover glass and housing glass when an impact is applied, such as when a smartphone or tablet is dropped. 20N or more) is required.

On the other hand, in recent years, as display devices have been further reduced in weight, the materials used inside have been made thinner. In the adhesive layer used, it has been conventionally used at about 25 μm, but it is mainly used in a thin film (for example, 5 μm), and it is necessary to exhibit high adhesiveness in the thin film. Along with this, a heat treatment sticking method has begun to be adopted as a method for improving the adhesiveness of the shatterproof film to the cover glass and the housing glass. In the conventional sticking method, the shatterproof film was stuck on the cover glass and the housing glass without heat treatment, but it is stuck on the cover glass and the housing glass by heat treatment (for example, 30 minutes in an atmosphere of 150 ° C.). A method for improving the adhesion of the glass is used. In the case of the sticking method by heat treatment, if the heat resistance of the adhesive is insufficient, the adhesive may squeeze out from the edge of the film. The pressure-sensitive adhesive used for the shatterproof film is required to have heat resistance, and after the heat treatment, higher adhesiveness than before is required.

In addition, with the recent 5G support, the volume of electronic components such as capacitors and coils installed inside smartphones and tablets is increasing. As a result, indentations may remain on the housing glass film due to the pressing of the electronic components, which may cause a problem of poor appearance. The adhesive used for the housing glass film needs to have dent resistance to prevent indentation caused by electronic components.

As a shatterproof film, Patent Document 1 discloses a pressure-sensitive adhesive containing a polymer and carbodiimide, having a gel fraction of 10% or more and an acid value of 50 mgKOH / g or less.

Further, Patent Document 2 comprises a structural unit derived from a (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 4 carbon atoms and a structural unit derived from a monomer having a carboxy group. Disclosed are a (meth) acrylic copolymer having a glass transition temperature of −35 ° C. or higher and −10 ° C. or lower and a weight average molecular weight of 450,000 or higher and 900,000 or lower, and a pressure-sensitive adhesive containing a cross-linking agent. There is.

Japanese Unexamined Patent Publication No. 2020-70313 Japanese Unexamined Patent Publication No. 2020-132788

These adhesives had a level of adhesiveness that would not cause any problems in practical use when used as a conventional cover glass film, but they have higher adhesiveness with a thinner film or heat resistance that can withstand the application method by heat treatment. Gender is not enough. In addition, when used as a film for housing glass, it cannot satisfy the dent resistance for preventing indentation due to electronic components.

That is, the present invention can satisfy the high adhesiveness and heat resistance required for the shatterproof film even with a thin film, and the dent resistance required for the housing glass film. It is an object of the present invention to provide an adhesive capable of producing an adhesive sheet having excellent properties.

As a result of diligent studies by the present inventor, it has been found that the problems of the present invention can be solved in the following aspects, and the present invention has been completed.
That is, the pressure-sensitive adhesive composition according to the present invention contains an acrylic copolymer (A), an epoxy resin (B), and a curing agent (C), and the acrylic copolymer (A) is the following monomer (a). -1) It is a copolymer of a monomer mixture containing (a-3), and the monomer (a-1) is 10 to 50% by mass and the monomer (a-2) is 40 to 40% by mass in 100% by mass of the monomer mixture. The epoxy resin (B) is a bisphenol type epoxy resin having a weight average molecular weight (Mw) of 200 to 1000, containing 80% by mass and 5 to 10% by mass of the monomer (a-3).
(A-1) A (meth) acrylic acid alkyl ester monomer having an alkyl group having 8 to 12 carbon atoms (a-2) A (meth) acrylic acid ester monomer having a glass transition temperature of 0 to 100 ° C. for a homopolymer (however, however) Excluding monomers (a-1) and (a-3))
(A-3) (Meth) acrylic acid alkyl ester monomer having a carboxyl group

INDUSTRIAL APPLICABILITY According to the present invention, high adhesiveness and heat resistance, which are the required qualities for a shatterproof film, can be satisfied even with a thin film, and dent resistance required for a housing glass film. Can also provide an excellent adhesive sheet.
Further, since it is excellent in transparency, it can be suitably used as a shatterproof film used for an optical member.

The terms used herein are defined. The (meth) acrylic acid ester includes an acrylic acid ester and a methacrylic acid ester. The monomer is an ethylenically unsaturated group-containing monomer. The adherend is the other party to which the adhesive sheet is attached. Sheets, films and tapes are synonyms in the present invention.
In the present specification, the glass transition of the acrylic copolymer (A), (a-1) a (meth) acrylic acid alkyl ester monomer having an alkyl group having 8 to 12 carbon atoms, and (a-2) a homopolymer. A (meth) acrylic acid ester monomer having a temperature of 0 to 100 ° C., a (meth) acrylic acid alkyl ester monomer having a carboxyl group (a-3), and a bisphenol type epoxy resin having a weight average molecular weight (Mw) of 300 to 1000 ( B) may be abbreviated as a copolymer (A), a monomer (a-1), a monomer (a-2), a monomer (a-3), and an epoxy resin (B), respectively.
Unless otherwise specified, the various components appearing in the present specification may be used independently or in combination of two or more.
Hereinafter, embodiments of the present invention will be described in detail, but the following description is an example (representative example) of embodiments of the present invention, and the present invention is not limited to these contents as long as the gist thereof is not exceeded.

The pressure-sensitive adhesive composition of the present invention contains an acrylic copolymer (A), an epoxy resin (B), and a curing agent (C).
The acrylic copolymer (A) is a copolymer of a monomer mixture containing the following monomers (a-1) to (a-3).
The monomer (a-1) is contained in an amount of 10 to 50% by mass, the monomer (a-2) is contained in an amount of 40 to 80% by mass, and the monomer (a-3) is contained in an amount of 5 to 10% by mass in 100% by mass of the monomer mixture.
The epoxy resin (B) is a bisphenol type epoxy resin having a weight average molecular weight (Mw) of 200 to 1000.
(A-1) A (meth) acrylic acid alkyl ester monomer having an alkyl group having 8 to 12 carbon atoms (a-2) A (meth) acrylic acid ester monomer having a glass transition temperature of 0 to 100 ° C. for a homopolymer (however, however) Excluding monomers (a-1) and (a-3))
(A-3) (Meth) acrylic acid alkyl ester monomer having a carboxyl group

The pressure-sensitive adhesive composition of the present invention preferably forms a pressure-sensitive adhesive layer by coating and is preferably used as a pressure-sensitive adhesive sheet provided with a base material. The pressure-sensitive adhesive sheet is preferably used as, for example, an optical pressure-sensitive adhesive sheet used for an optical member.

《Adhesive composition》
The pressure-sensitive adhesive composition of the present invention comprises a (meth) acrylic acid alkyl ester monomer (a-1) having an alkyl group having 8 to 12 carbon atoms as a monomer constituting the acrylic copolymer (A), and a homopolymer. Adhesion is achieved by using a specific amount of each of a (meth) acrylic acid ester monomer (a-2) having a glass transition temperature of 0 to 100 ° C. and a (meth) acrylic acid alkyl ester monomer (a-3) having a carboxyl group. Since the layer has the trade-off property of achieving both hardness and softness, even if the adhesive layer is a thin film, both high adhesiveness and heat resistance can be achieved, and dent resistance is also excellent. be able to.

The pressure-sensitive adhesive composition of the present invention is suitable as a pressure-sensitive adhesive sheet, as a raw material for various plastic sheets, general labels / seals, pressure-sensitive adhesives, pressure-sensitive adhesives for laminated structures, and sealing agents, and as various resin additives. And it can be used very usefully as a raw material thereof.

<Acrylic copolymer (A)>
The acrylic copolymer (A) in the present specification is a (meth) acrylic acid alkyl ester monomer (a-1) having an alkyl group having 8 to 12 carbon atoms, and the homopolymer has a glass transition temperature of 0 to 100 ° C. It is a copolymerization of a monomer mixture containing a (meth) acrylic acid ester monomer (a-2) and a (meth) acrylic acid alkyl ester monomer (a-3) having a carboxyl group.
Further, the monomer (a-1) is contained in an amount of 10 to 50% by mass, the monomer (a-2) is contained in an amount of 40 to 80% by mass, and the monomer (a-3) is contained in an amount of 5 to 10% by mass in 100% by mass of the monomer mixture. ..
Other monomers may be used in combination as long as the effects of the present invention are not impaired.

[Monomer (a-1)]
The monomer (a-1) is a (meth) acrylic acid alkyl ester monomer having an alkyl group having 8 to 12 carbon atoms. However, the monomer (a-3) is excluded.
By containing the monomer (a-1), sufficient wettability and cohesiveness can be imparted to the adhesive layer, and adhesion to the substrate can be improved. When the number of carbon atoms is less than 8, the flexibility of the adhesive layer is lowered and the adhesion to the substrate is lowered. Further, when the number of carbon atoms exceeds 12, the rigidity of the adhesive layer is lowered and the durability is lowered.

The monomer (a-1) is, for example, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, (meth). Examples thereof include undecylic acid (meth) and dodecyl (meth) acrylate.

Among the monomers (a-1), 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, and dodecyl (meth) acrylate are preferable in terms of achieving both flexibility and cohesiveness.

The content of the monomer (a-1) is 10 to 50% by mass, more preferably 20 to 40% by mass, based on 100% by mass of the monomer mixture. When the content is 10% by mass or more, sufficient adhesiveness is obtained, and when the content is 50% by mass or less, both adhesive strength, heat resistance and dent resistance are compatible at a high level. can.

[Monomer (a-2)]
The monomer (a-2) is a (meth) acrylic acid ester monomer having a glass transition temperature (Tg) of the homopolymer of 0 to 100 ° C. However, the monomers (a-1) and (a-3) are excluded.
By containing the monomer (a-2), sufficient cohesiveness can be imparted to the adhesive layer, and adhesion to the substrate can be improved. When the glass transition temperature of the homopolymer is less than 0 ° C., the rigidity of the adhesive layer is lowered and the heat resistance is lowered. Further, when the glass transition temperature of the homopolymer exceeds 100 ° C., the flexibility of the adhesive layer is lowered and the adhesiveness is lowered.
A (meth) acrylic acid ester monomer having a Tg of 5 to 100 ° C. is more preferable, and a (meth) acrylic acid ester monomer having a Tg of 10 to 95 ° C. is more preferable.
Here, the monomer having a glass transition temperature of the homopolymer of 0 to 100 ° C. means a monomer having a Tg of 0 to 100 ° C. when the homopolymer is formed by polymerization. As the Tg of the homopolymer, published values such as literature values and catalog values can be used.

The monomer (a-2) is, for example, a (meth) acrylic acid alkyl ester monomer having a homopolymer glass transition temperature of 0 to 100 ° C., and an alicyclic (meth) acrylic having a homopolymer glass transition temperature of 0 to 100 ° C. Acid ester monomers, aromatic (meth) acrylic acid ester monomers with a homopolymer glass transition temperature of 0 to 100 ° C, amino group-containing (meth) acrylic acid ester monomers with a homopolymer glass transition temperature of 0 to 100 ° C, etc. Can be mentioned.

Examples of the (meth) acrylic acid alkyl ester monomer having a homopolymer glass transition temperature of 0 to 100 ° C. include methyl (meth) acrylic acid, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate and methacrylic acid. Examples thereof include isobutyl and t-butyl methacrylate.

Examples of the alicyclic (meth) acrylic acid ester monomer having a glass transition temperature of the homopolymer of 0 to 100 ° C. include cyclohexyl (meth) acrylate and isobornyl acrylate.

Examples of the aromatic (meth) acrylic acid ester monomer having a glass transition temperature of the homopolymer of 0 to 100 ° C. include benzyl (meth) acrylate and phenoxyethyl (meth) acrylate.

Examples of the amino group-containing monomer having a glass transition temperature of the homopolymer of 0 to 100 ° C. include dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate.

Methyl (meth) acrylate, isobornyl acrylate, (meth) in terms of achieving both flexibility and cohesiveness among (meth) acrylic acid ester monomers (a-2) having a homopolymer glass transition temperature of 0 to 100 ° C. Benzyl acrylate and dimethylaminoethyl methacrylate are preferable, and methyl (meth) acrylate and isobornyl acrylate are more preferable from the viewpoint of heat resistance and dent resistance.

The content of the monomer (a-2) is 40 to 80% by mass, more preferably 30 to 70% by mass in 100% by mass of the monomer mixture. When the content is 40% by mass or more, sufficient cohesive force is obtained to improve heat resistance, and when the content is 80% by mass or less, transparency, heat resistance and adhesion are high. It is compatible with the standard.

[Monomer (a-3)]
The monomer (a-3) is a (meth) acrylic acid alkyl ester monomer having a carboxyl group. If the homopolymer has an alkyl group having 8 to 12 carbon atoms, or if the homopolymer has a (meth) acrylic acid ester monomer having a glass transition temperature (Tg) of 0 to 100 ° C. but has a carboxyl group, the monomer is used. Corresponds to (a-3).
By containing the monomer (a-3), sufficient rigidity can be imparted to the adhesive layer, and heat resistance is improved. Further, since the polarity of the adhesive layer is increased, the adhesion to the highly polar adherend is improved.

Examples of the monomer (a-3) include (meth) acrylic acid, p-carboxybenzyl acrylate, β-carboxyethyl acrylate, maleic acid, monoethylmaleic acid, itaconic acid, citraconic acid, fumaric acid and the like. ..
Among these, (meth) acrylic acid is preferable in terms of ensuring sufficient adhesiveness.

The content of the monomer (a-3) is 5 to 15% by mass, more preferably 5 to 10% by mass, based on 100% by mass of the monomer mixture. When the content is 5% by mass or more, sufficient cohesive force is obtained and heat resistance is improved, and when the content is 15% by mass or less, sufficient adhesion can be ensured. , Adhesiveness is improved.

[Other monomers]
As the copolymer (A), other monomers can be used in addition to the monomer (a-1), the monomer (a-2), and the monomer (a-3).
Other monomers include (meth) acrylic acid alkyl ester monomers and hydroxyl groups having a homopolymer glass transition temperature of less than 0 ° C. other than the (meth) acrylic acid alkyl ester monomer (a-1) having an alkyl group having 8 to 12 carbon atoms. Examples thereof include a (meth) acrylic acid alkyl ester monomer having an epoxy group, a monomer having an amide bond, a (meth) acrylic acid monomer having an epoxy group, and a vinyl monomer.

A (meth) acrylic acid alkyl ester monomer having a glass transition temperature of less than 0 ° C. of a homopolymer other than the (meth) acrylic acid alkyl ester monomer (a-1) having an alkyl group having 8 to 12 carbon atoms is, for example, acrylic acid. Examples thereof include ethyl, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and t-butyl acrylate.

Examples of the (meth) acrylic acid alkyl ester monomer having a hydroxyl group include (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 2-hydroxypropyl, (meth) acrylic acid 3-hydroxypropyl, and (meth) acrylic acid. Examples thereof include 2-hydroxybutyl, (meth) acrylic acid, and 4-hydroxybutyl (meth) acrylic acid.

Monomers having an amide bond include, for example, (meth) acrylamide, N-methylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-diacetone, N, N-dimethylaminopropyl (meth) acrylamide, (Meta) acrylamide-based compounds such as diacetone acrylamide, N- (butoxymethyl) acrylamide;
Examples thereof include compounds having a heterocycle such as N-vinylpyrrolidone, N-vinylcaprolactam, and acryloylmorpholine.

Monomers having an epoxy group include, for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, and 6-methyl-3,4-methyl (meth) acrylate. Epoxy cyclohexylmethyl and the like can be mentioned.

Examples of the vinyl monomer include vinyl acetate, vinyl crotonic acid, styrene, acrylonitrile and the like.

The content of the other monomer is preferably 5 to 30% by weight in 100% by mass of the monomer mixture. When the content is 5% by weight or more, the adhesion is further improved. Further, when the content is 30% by weight or less, it is easy to achieve both cohesive force and adhesion.

[Method for producing copolymer (A)]
The copolymer (A) can be synthesized by polymerizing a monomer mixture. As the polymerization, known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization and suspension polymerization are possible, but solution polymerization is preferable. As the solvent used in the solution polymerization, for example, acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, cyclohexanone and the like are preferable.
The polymerization temperature is preferably a boiling point reaction at 60 to 120 ° C. The polymerization time is preferably about 5 to 12 hours.

The polymerization initiator used for the polymerization is preferably a radical polymerization initiator. The radical polymerization initiator is generally a peroxide or an azo compound.
Peroxides include, for example, di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-. Dialkyl peroxides such as di (t-butylperoxy) hexin-3;
Peroxyesters such as t-butylperoxybenzoate, t-butylperoxyacetate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane; cyclohexanone peroxide, 3,3,5-trimethylcyclohexanoneper Ketone peroxides such as oxides and methylcyclohexanone peroxides;
2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-) Butylperoxy) cyclohexane, n-butyl-4,4-bis (t-butylperoxy) barate, and other peroxyketals;
Hydroperoxides such as cumenehydroperoxide, diisopropylbenzenehydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide;
Diacyl peroxides such as benzoyl peroxide, decanoyle peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide;
Examples thereof include peroxydicarbonates such as bis (t-butylcyclohexyl) peroxydicarbonate.

The azo compound is, for example, 2,2'-azobisisobutyronitrile such as 2,2'-azobisisobutyronitrile (abbreviation: AIBN), 2,2'-azobis (2-methylbutyronitrile);
2,2'-Azobisvaleronitrile such as 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile);
2,2'-azobis propionitrile such as 2,2'-azobis (2-hydroxymethylpropionitrile);
Examples thereof include 1,1'-azobis-1-alkanenitrile such as 1,1'-azobis (cyclohexane-1-carbonitrile).

The polymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the monomer mixture.

The weight average molecular weight of the copolymer (A) is preferably 300,000 to 1.8 million, more preferably 500,000 to 1.2 million. When it is in the range of 300,000 to 1.8 million, the cohesive force is further improved, and the moisture resistance and heat resistance are further improved. The weight average molecular weight and the number average molecular weight are polystyrene-equivalent values measured by a gel permeation chromatography (GPC) method. Details of the measurement method of GPC are described in Examples.

<Epoxy resin (B)>
The epoxy resin (B) is a bisphenol type epoxy resin having a weight average molecular weight (Mw) of 200 to 1000. By containing the epoxy resin (B), high adhesion to the adherend is exhibited. In particular, when used with the adhesive layer of a housing glass film, the hardness of the adhesive after heat treatment can be improved, and high heat resistance and dent resistance are exhibited.

The epoxy resin (B) is a compound having a bisphenol skeleton as shown by -O-Ph-CR ¹ R ² -Ph-O- in the molecule and having an epoxy group as a functional group. Ph is an aromatic hydrocarbon group, and R ¹ and R ² are independently hydrogen atoms or methyl groups, respectively. Examples of such bisphenol type epoxy resin (B) include JER825 (Mw = 350), JER828 (Mw = 370), JER806 (Mw = 330), JER1001 (Mw = 900) (all manufactured by Mitsubishi Chemical Corporation). Can be mentioned.

The weight average molecular weight (Mw) of the epoxy resin (B) is 200 to 1000, more preferably 300 to 900. When the weight average molecular weight (Mw) is 200 or more, sufficient cohesive force is obtained, and heat resistance and dent resistance are improved. Further, when the weight average molecular weight (Mw) is 1000 or less, transparency and sufficient adhesion can be ensured, adhesiveness is improved, and heat resistance and dent resistance are improved.

The epoxy resin (B) preferably contains 5 to 45 parts by mass, more preferably 10 to 40 parts by mass, based on 100 parts by mass of the acrylic copolymer (A). When the content is 5 parts by mass or more, sufficient cohesive force can be easily obtained, and when the content is 45 parts by mass or less, sufficient adhesion can be ensured and the adhesiveness is improved.

<Curing agent (C)>
By reacting the curing agent (C) with the carboxyl group of the copolymer (A), the cohesive force of the adhesive layer is improved, and the adhesiveness, heat resistance and dent resistance are further improved.

Examples of the curing agent (C) include an isocyanate compound, an epoxy compound, an aziridine compound, a carbodiimide compound, and a metal chelate. However, the epoxy resin (B) is excluded.
Of these, the isocyanate compound is preferable from the viewpoint of achieving both high cohesive force and adhesion. By using an isocyanate compound, heat-resistant adhesiveness can be improved.

The isocyanate compound is an isocyanate having two or more isocyanate groups. As the isocyanate compound, for example, isocyanate monomers such as aromatic polyisocyanates, aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, and alicyclic polyisocyanates, and their bullets, nurates, and adducts are preferable.

The aromatic polyisocyanate is, for example, 1,3-phenylenediocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6- Tolylene diisocyanate, 4,4'-toluene diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4', 4 "-Triphenylmethane triisocyanate and the like can be mentioned.

The aliphatic polyisocyanate includes, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylenedisocyanate, 1,3-butylenedisisisus, and the like. Dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate and the like can be mentioned.

The aromatic aliphatic polyisocyanate is, for example, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1,4-diethylbenzene, Examples thereof include 1,4-tetramethylxylylene diisocyanate and 1,3-tetramethylxylylene diisocyanate.

The alicyclic polyisocyanate is, for example, 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, 1,4. -Cyclohexanediisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,4-bis (isocyanatemethyl) cyclohexane and the like can be mentioned.

The burette body is a self-condensed product having a burette bond in which an isocyanate monomer is self-condensed. Examples of the burette body include a burette body of hexamethylene diisocyanate.

The nurate form is a trimer of an isocyanate monomer. For example, a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, a trimer of tolylene diisocyanate, and the like can be mentioned.

The adduct is a bifunctional or higher functional isocyanate compound obtained by reacting an isocyanate monomer with a bifunctional or higher functional small molecule active hydrogen-containing compound. The adduct can be, for example, a compound obtained by reacting trimethylolpropane with hexamethylene diisocyanate, a compound obtained by reacting trimethylolpropane with trilenidisocyanate, a compound obtained by reacting trimethylolpropane with xylylene diisocyanate, or trimethylol. Examples thereof include a compound obtained by reacting propane with isophorone diisocyanate, a compound obtained by reacting 1,6-hexanediol with hexamethylene diisocyanate, and the like.

The isocyanate compound is preferably a trifunctional isocyanate compound from the viewpoint of forming a sufficient crosslinked structure. The isocyanate compound is more preferably an adduct-form or a nurate-form, which is a reaction product of an isocyanate monomer and a trifunctional small molecule active hydrogen-containing compound. The isocyanate compounds are hexamethylene diisocyanate trimetylolpropane adduct, hexamethylene diisocyanate nurate, tolylene diisocyanate trimethylolpropane adduct, tolylene diisocyanate nurate, isophorone diisocyanate trimetylolpropane adduct, and isophorone diisocyanate. Nurate is preferable, and trimethylolpropane adduct of hexamethylene diisocyanate, trimethylolpropane adduct of tolylene diisocyanate, and trimethylolpropane adduct of isophorone diisocyanate are more preferable.

Epoxy compounds include, for example, glycerin diglycidyl ether, 1,6-hexanediol diglycidyl ether, N, N, N', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N'-. Diglycidylaminomethyl) cyclohexane, N, N, N', N'-tetraglycidylaminophenylmethane and the like can be mentioned.

Aziridine compounds include, for example, N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxysite), tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, 4, Examples thereof include 4'-bis (ethyleneiminocarbonylamino) diphenylmethane.

The carbodiimide compound is preferably a high molecular weight polycarbodiimide produced by decarboxylating and condensing the diisocyanate compound in the presence of a carbodiimideization catalyst. The commercially available high molecular weight polycarbodiimide is preferably the carbodilite series manufactured by Nisshinbo. Among them, Carbodilite V-03, 07, 09 is preferable because it has excellent compatibility with an organic solvent.

The metal chelate is preferably a coordination compound of a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium with acetylacetone or ethyl acetoacetate. Examples of the metal chelate include aluminum ethyl acetoacetate / diisopropyrate, aluminum trisacetylacetonate, aluminum bisethylacetate / monoacetylacetone, and aluminum alkylacetate / diisopropyrate.

The curing agent (B) is preferably contained in an amount of 0.01 to 5 parts by mass, more preferably 0.01 to 2 parts by mass with respect to 100 parts by mass of the copolymer (A). When the content is 0.01 part by mass or more, the cohesive force is further improved, and when the content is 5 parts by mass or less, it is easy to achieve both the cohesive force and the flexibility, which is preferable.

<Silane coupling agent (D)>
The pressure-sensitive adhesive composition of the present invention may contain a silane coupling agent (D) as long as the problem can be solved. By containing the silane coupling agent (D), the adhesion to the glass is improved, and in particular, the heat-resistant adhesiveness after the heat treatment is dramatically improved.

The silane coupling agent (D) is, for example, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltripropoxysilane, 3-( An alkoxysilane compound having a (meth) acryloxy group, such as (meth) acryloxipropyltributoxysilane, 3- (meth) acryloxipropylmethyldimethoxysilane, 3- (meth) acryloxipropylmethyldiethoxysilane;
Alkoxysilane compounds having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane;
3-Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl)- 3-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) An alkoxysilane compound having an amino group such as -3-aminopropylmethyldiethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane;
An alkoxysilane compound having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane;
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, An alkoxysilane compound having an epoxy group such as 3-glycidoxypropylmethyldiethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane;
Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane;
3-Chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-Triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, 1,3,5-tris (3-trimethoxysilylpropyl) isocyanurate, 3-Isoxypropyltrimethoxysilane, 3-Isoxypropyl Examples thereof include triethoxysilane, hexamethyldisilazane, and silicone resins having an alkoxysilyl group in the molecule.

The silane coupling agent (D) is preferably used in an amount of 0.01 to 2 parts by mass, more preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the copolymer (A).

<Arbitrary ingredient>
The pressure-sensitive adhesive composition of the present invention is filled with various resins, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weather-resistant stabilizers, plasticizers, and fillers as optional components as long as the problems can be solved. It can contain agents, anti-aging agents, anti-static agents and the like.

《Adhesive sheet》
The pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition. Above all, it is preferable to provide a base material and a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive sheet is produced, for example, by applying a pressure-sensitive adhesive composition on a base material and drying it to form a pressure-sensitive adhesive layer. Further, it is also possible to form an adhesive layer by applying an adhesive composition to a peelable sheet and drying it, and to bond the base materials to each other. Further, the surface of the adhesive layer that is not in contact with the base material is usually used by laminating a peelable sheet until immediately before use in order to prevent foreign matter from adhering. The drying temperature is usually about 60 to 150 ° C.
The thickness of the adhesive layer is usually about 0.1 to 200 μm.
The pressure-sensitive adhesive composition of the present invention can be used in a thickness within the range normally used, and even if it is a thin film of 0.1 to 30 μm, further 0.1 to 10 μm, it has adhesiveness and heat resistance. It has an excellent effect that it can be sufficiently achieved.

Examples of the coating method include known methods such as a roll coater method, a comma coater method, a die coater method, a reverse coater method, a silk screen method, and a gravure coater method.

When applying the pressure-sensitive adhesive composition, the viscosity can be adjusted with a solvent. The solvent is, for example, a hydrocarbon solvent such as toluene, xylene, hexane, heptane; an ester solvent such as ethyl acetate or butyl acetate; a ketone solvent such as acetone or methyl ethyl ketone; a halogenated hydrocarbon solvent such as dichloromethane or chloroform. ; Examples include ether solvents such as diethyl ether, methoxytoluene, and dioxane.

As the base material, flexible sheets and plate materials can be used without limitation. Examples of the base material include plastic, paper, and metal foil, and laminates thereof and the like.
In order to improve the adhesion to the surface of the base material in contact with the adhesive layer, easy adhesion treatment such as dry treatment such as corona discharge treatment or wet treatment such as coating of an anchor coating agent can be performed in advance.
As the base material, a laminated body obtained by laminating a single optical film or a plurality of optical films can be used.
The thickness of the base material is usually about 10 to 250 μm.

As the release sheet, a known release sheet in which the surface of plastic or paper is subjected to a known release treatment such as a silicone-based release agent can be used.
The thickness of the peelable sheet is usually about 10 to 250 μm.

The adherend can be used without any particular restrictions. The adherend is general-purpose glass, building materials, polyolefins, ABS, polystyrene, acrylics and other plastics, cardboard, wood, plywood, stainless steel, aluminum and other metals, and for example, non-alkali glass, which is optical glass, polarizing plates, and elliptically polarized light. Examples thereof include optical members such as films, transparent conductive films, retardation films, antireflection films, brightness improving films, and super water repellent glass.
The pressure-sensitive adhesive sheet of the present invention can be suitably used as an optical pressure-sensitive adhesive sheet used for an optical member as an adherend.

<Optical adhesive sheet>
The pressure-sensitive adhesive layer, which is a cured product of the pressure-sensitive adhesive composition of the present invention, has excellent transparency and can be suitably used as an optical pressure-sensitive adhesive sheet.
The optical adhesive sheet is an adhesive sheet used by being attached to an optical member, and is suitable as a surface protective sheet for display devices and the like. In addition, it has excellent adhesiveness and heat resistance in thin films, good anti-scattering properties, and excellent dent resistance to prevent indentations caused by electronic components, so it can be used as a cover glass film. Not only that, it can also be suitably used as a film for housing glass.

When the optical pressure-sensitive adhesive sheet has a base material, it is preferable that the optical pressure-sensitive adhesive sheet includes an optical film as the base material and a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition.
The optical pressure-sensitive adhesive sheet is produced, for example, by applying a pressure-sensitive adhesive composition to an optical film and drying it to form a pressure-sensitive adhesive layer. Further, it is also possible to form an adhesive layer by applying an adhesive composition to a peelable sheet and drying it, and to bond an optical film to the sheet. Further, the surface of the adhesive layer that is not in contact with the optical film is usually used by laminating a peelable sheet until immediately before use in order to prevent foreign matter from adhering. The drying temperature is usually about 60 to 150 ° C. The thickness of the adhesive layer is usually about 0.1 to 200 μm.

The optical film is a transparent and light-transmitting film, for example, polyvinyl alcohol, triacetyl cellulose, polyolefin (polypropylene, polyethylene), polycycloolefin, ethylene-vinyl acetate copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene. Polyester resin such as naphthalate, polyacrylic resin such as polymethylmethacrylate and polybutylmethacrylate, polycarbonate resin, polynorbornene resin, polyallylate resin, polyacrylic resin, polyphenylene sulfide resin, polystyrene resin, polyamide resin, polyimide resin, Examples include epoxy resins.

The optical adhesive sheet of the present invention can be suitably used as a shatterproof film for optical members. Examples of the optical member include optical glass, water-repellent treated glass, decorative printing glass, polarizing plate, elliptically polarizing film, transparent conductive film, retardation film, antireflection film, brightness improving film, and the like.

Here, the superhydrophobic glass is a surface-treated glass in which a hydrophobic substance such as fluorine or silicon is coated or vapor-deposited on the glass surface and then fine irregularities of 10 to 500 nm are formed on the surface, and is oil-repellent and water-repellent. It is a material that combines both. This makes it possible to highly prevent surface contamination due to moisture, sweat, and sebum.

The use of the optical adhesive sheet of the present invention is not particularly limited, but for example, various electronics-related members such as liquid crystal displays, organic EL displays, plasma displays, touch screen panels, car navigation systems, in-vehicle interior display devices, and electrode peripheral members. It can also be applied as a shatterproof film.

In addition, in recent years, shatterproof films for display devices such as smartphones and tablets have heat resistance in the heat treatment process, which was not required in the past, and dent resistance against pressing of electronic parts such as capacitors and coils installed inside. Sex is required.

As described above, in the pressure-sensitive adhesive composition of the present invention, which is composed of the copolymer (A), the epoxy resin (B), and the curing agent (C), the copolymer (A) has a long chain (meth). By including both the structural unit derived from the acrylic acid alkyl ester monomer and the structural unit derived from the high Tg (meth) acrylic acid ester monomer in a specific content, the adhesion to the glass is dramatically improved, and the adhesiveness and heat resistance are improved. Can be compatible with each other. Further, by containing the epoxy resin (B), high dent resistance can be exhibited without impairing the adhesiveness, and the film can be applied as a shatterproof film. Further, by containing the curing agent (C), the cohesive force of the adhesive layer is improved, and the adhesiveness, heat resistance and dent resistance are excellent.
In addition, the pressure-sensitive adhesive composition of the present invention can be used in a thickness within the range normally used, and can sufficiently achieve adhesiveness and heat resistance even if it is a thinner film than before. It has an excellent effect.

Next, examples will be given and further described in detail, but the present invention is not limited thereto. In the example, unless otherwise specified, "parts" indicates "parts by mass" and "%" indicates "% by mass". The blending amount in the table is a part by mass, and is a non-volatile content conversion value except for the solvent. The blanks in the table indicate that they are not mixed. Further, the Tg of the monomer used in the following example indicates the Tg of the homopolymer. For the Tg of the homopolymer, published values such as literature values and catalog values were used.
The method for measuring the weight average molecular weight of the copolymer is as follows.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) was measured by using a GPC "LC-GPC system" manufactured by Shimadzu Corporation. The weight average molecular weight (Mw) was determined by using polystyrene having a known molecular weight as a standard material.
Device name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation
Column: 4 GMHXL manufactured by Tosoh Co., Ltd. and 1 HXL-H manufactured by Tosoh Co., Ltd. were connected.
Mobile phase solvent: Tetrahydrofuran flow rate: 1.0 ml / min Column temperature: 40 ° C

<Manufacturing of acrylic copolymer>
(Synthesis Example 1: Copolymer (A))
10 parts of 2-ethylhexyl acrylate (EHA), methyl acrylate in a reaction vessel (hereinafter simply referred to as "reaction vessel") equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube. (MA) 80 parts, acrylic acid 10 parts, ethyl acetate 100 parts, 2,2'-azobisisobutyronitrile (hereinafter referred to as AIBN) 0.2 parts were charged, and the atmosphere in this reaction vessel was heated with nitrogen gas. Replaced. Then, the reaction was started by heating to 65 ° C. while stirring in a nitrogen atmosphere. Then, the reaction solution was reacted at 65 ° C. for 4 hours. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a copolymer (A-1) solution having a non-volatile content of 30%. The weight average molecular weight of the obtained copolymer (A-1) was 1.8 million.

(Synthesis Examples 2 to 18)
An acrylic copolymer was produced by the same method as in Synthesis Example 1 except that the raw materials and the amounts used were changed according to the mass ratio in Table 1. The weight average molecular weight (Mw) of the obtained copolymer is shown in Table 1.

[Monomer (a-1)]
EHA: 2-ethylhexyl acrylate OTA: n-octyl acrylate DCA: dodecyl acrylate [monomer (a-2)]
MA: Methyl acrylate (Tg: 6 ° C)
IBXA: Isobornyl acrylate (Tg: 97 ° C)
BzA: Benzyl acrylate (Tg: 6 ° C)
DMAEMA: Dimethylaminoethyl methacrylate (Tg: 18 ° C)
[Monomer (a-3)]
AA: Acrylic acid MAA: Methacrylic acid [Other monomers]
BA: n-butyl acrylate EA: ethyl acrylate

(Example 1)
<Preparation of adhesive>
The epoxy resin (B-1) "JER825" (bisphenol type epoxy) is used as the epoxy resin (B) with respect to 100 parts by weight of the copolymer (A-1) in the obtained copolymer (A-1) solution. Resin, Mw = 350, manufactured by Mitsubishi Chemical Co., Ltd.) 5 parts by weight, as the curing agent (C), 0.01 part by weight of the curing agent (C-1) "Aduct body of trimethylolpropane of hexamethylene diisocyanate" is non-volatile. Epoxy acetate was added so that the ratio was 20%, and the mixture was stirred to obtain a pressure-sensitive adhesive solution.

<Making an adhesive sheet>
The obtained adhesive solution is applied onto a peelable sheet (polyethylene terephthalate (PET), "E7004", silicone-based peeling layer, manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm so that the thickness after drying is 5 μm. Then, it was dried at 120 ° C. for 3 minutes to form an adhesive layer. Next, one side of a peelable sheet (polyethylene terephthalate, "SP-PET3811", silicone-based peeling layer, manufactured by Lintec Corporation) having a thickness of 38 μm is bonded to this adhesive layer to form a “peeling sheet / adhesive layer / peelable sheet”. The laminated body of was produced. Then, the obtained laminate was aged for one week under the condition of a temperature of 25 ° C. and a relative humidity of 55% to obtain an adhesive sheet.

(Examples 2 to 12, Comparative Examples 1 to 8)
As shown in Table 2, a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the copolymer, epoxy resin, type of curing agent, and blending amount were changed.

(Example 13)
<Preparation of adhesive>
JER825 (bisphenol type epoxy resin, Mw = 350, manufactured by Mitsubishi Chemical Co., Ltd.) as the epoxy resin (B) with respect to 100 parts by weight of the copolymer (A-2) in the copolymer (A-2) solution. 5 parts by weight, 1.0 part by weight of the adduct body (I-1) of trimethylolpropane of tolylene diisocyanate as the curing agent (C), and 3-glycidoxypropyltriethoxysilane as the silane coupling agent (D). Ethyl acetate was blended so that 0.1 part by weight and the non-volatile content was 20%, and the mixture was stirred to obtain a pressure-sensitive adhesive solution.

<Making an adhesive sheet>
An adhesive sheet was obtained according to the procedure for producing the adhesive sheet of Example 1.

(Examples 14 to 18)
As shown in Table 2, a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 13 except that the copolymer, epoxy resin, type of curing agent, and blending amount were changed.

[Epoxy resin (B)]
B-1: JER825
(Bisphenol type epoxy resin, Mw = 350, manufactured by Mitsubishi Chemical Corporation)
B-2: JER828
(Bisphenol type epoxy resin, Mw = 370, manufactured by Mitsubishi Chemical Corporation)
B-3: JER806
(Bisphenol type epoxy resin, Mw = 330, manufactured by Mitsubishi Chemical Corporation)
B-4: JER1001
(Bisphenol type epoxy resin, Mw = 900, manufactured by Mitsubishi Chemical Corporation)
[Curing agent (C)]
C-1: Hexamethylene diisocyanate trimethylolpropane adduct body C-2: Tolylene diisocyanate trimethylolpropane adduct body C-3: Isophorone diisocyanate trimethylolpropane adduct body C-4: N, N, N', N '-Tetraglycidyl-m-xylylene diisamine [silane coupling agent (D)]
D-1: 3-glycidoxypropyltriethoxysilane

Using the obtained adhesive sheet, as a film test for cover glass and a film for housing glass, transparency, adhesiveness, heat resistance, heat resistance, shatterproofness, and impact resistance were tested for the film for housing glass. As a result, the dent resistance was evaluated.

<< Preparation of test laminate >>
[Test laminate 1: PET film / adhesive layer / glass]
The obtained pressure-sensitive adhesive sheet was cut into a size of 25 mm in width and 100 mm in length to prepare a test pressure-sensitive adhesive sheet 1 composed of a PET film / pressure-sensitive adhesive layer / peelable sheet.
The peelable sheet was peeled off from the test adhesive sheet 1, and the exposed adhesive layer was attached to a non-alkali glass plate (EN-A1: manufactured by Asahi Glass Co., Ltd.) at 25 ° C. and a relative humidity of 50% using a laminator. The one composed of the PET film / adhesive layer / glass was designated as the test laminate 1.

[Test laminate 2: PET film / adhesive layer / display]
The obtained pressure-sensitive adhesive sheet was cut into a size (corresponding to 6.1 inches) having a width of 75 mm and a length of 150 mm to prepare a test pressure-sensitive adhesive sheet 2 composed of a PET film / pressure-sensitive adhesive layer / peelable sheet.
The peelable sheet was peeled off from the test adhesive sheet 2, and the exposed adhesive layer was attached to the display of a smartphone (iPhone (registered trademark) 11: Apple) under an atmosphere of 25 ° C. and a relative humidity of 50% for testing. The laminated body 2 was used.

"Evaluation method"
<Transparency>
The test laminate 1 was left at 23 ° C. and a relative humidity of 50% for 1 week, and then HAZE was measured. HAZE was measured using a Turbidimeter NDH5000W manufactured by Nippon Denshoku Kogyo Co., Ltd.
[Evaluation criteria]
◯: HAZE is less than 1.0 (good).
X: HAZE is 1.0 or more (defective).

<Adhesiveness>
After leaving the test laminate 1 at 23 ° C. and a relative humidity of 50% for 24 hours, a 180 ° peel test was carried out in which the test laminate 1 was peeled off at a speed of 300 mm / min in the 180 ° direction. The peel strength at the time of peeling was measured, and the adhesiveness was evaluated in two stages.
[Evaluation criteria]
◯: "The peel strength is 20 N or more, and there is no problem in practical use."
Δ: "Peeling strength is 10 N or more and less than 20 N, but it is practical."
X: "Peeling strength is less than 10N, not practical"

<Heat-resistant adhesiveness>
The test laminate 1 is left in an atmosphere of 150 ° C. for 30 minutes, then allowed to stand in an atmosphere of 25 ° C. and a relative humidity of 50% RH for 30 minutes, and then peeled off at a speed of 300 mm / min in the 180 ° C. 180 ° peel. A test was conducted. The peel strength at the time of peeling was measured, and the adhesiveness was evaluated in three stages.
[Evaluation criteria]
◯: "The peel strength is 30 N or more, and there is no problem in practical use."
Δ: “Peeling strength is 20 N or more and less than 30 N, which is practical”
X: "Peeling strength is less than 20N, not practical"

<Heat resistance>
The test laminate 1 was left to stand in an atmosphere of 150 ° C. for 30 minutes, then allowed to stand in an atmosphere of 25 ° C. and a relative humidity of 50% for 30 minutes, and then the end portion of the test adhesive sheet was visually observed. The length of the pressure-sensitive adhesive protruding from the test pressure-sensitive adhesive sheet was measured, and the heat resistance was evaluated on a three-point scale.
[Evaluation criteria]
○: "There is no protrusion and there is no problem in practical use."
Δ: "The protrusion length is within 0.2 mm and is practical."
×: "The protruding length is larger than 0.2 mm, which is not practical"

<Impact resistance>
The test laminate 2 was dropped from a height of 1 m onto a concrete surface, and it was visually confirmed whether or not the test adhesive sheet 2 was peeled off from the information display surface of the display, and the impact resistance was evaluated in two stages. ..
[Evaluation criteria]
○: "There is no peeling and there is no problem in practical use"
×: "Peeling is confirmed and practical use is not possible"

<Scattering prevention>
The test laminate 2 was placed so that the display surface to which the test adhesive sheet 2 was attached faced up, and the test adhesive sheet 2 was attached from a height of 1.5 m with a 50 g stainless steel ball. It was visually confirmed whether or not the display glass was scattered when dropped on the display surface, and the anti-scattering property was evaluated in two stages.
[Evaluation criteria]
○: "The glass broke, but the fragments did not scatter around, and there was no problem in practical use."
×: "Glass is broken, and it is confirmed that the fragments are scattered around, so it is not practical."

<Spot resistance>
The test laminate 2 was allowed to stand in an atmosphere of 150 ° C. for 30 minutes, and then allowed to stand in an atmosphere of 25 ° C. and a relative humidity of 50% for 30 minutes. Twenty stainless steel beads having a diameter of 1 mm were placed on the test adhesive sheet 1, and a non-alkali glass plate (EN-A1: manufactured by Asahi Glass Co., Ltd.) was placed on the stainless steel beads. A weight weighing 500 g is placed on the top non-alkali glass plate, left at 25 ° C and 50% relative humidity for 24 hours, then the weight, non-alkali glass and stainless beads are removed, and the stainless beads are removed. The presence or absence of indentations due to pressing was visually confirmed, and the dent resistance was evaluated on a three-point scale.
[Evaluation criteria]
○: "There are no indentations and there is no problem in practical use."
Δ: "There are no more than 5 dents and it is practical"
×: "There are more indentations than 5 and it is not practical"

From the results shown in Table 3, it was confirmed that the pressure-sensitive adhesive composition of the present invention has excellent transparency and anti-scattering properties, and therefore can be suitably used as an anti-scattering film used for optical members.
Further, even if the film thickness is 5 μm, which is a thinner film than before, it has high adhesiveness and heat resistance, and also has good dent resistance required for a film for housing glass. I was able to confirm that.
On the other hand, the pressure-sensitive adhesive compositions of Comparative Examples 1 to 8 could not satisfy all of the above-mentioned characteristics.

Claims (6)

Contains an acrylic copolymer (A), an epoxy resin (B), and a curing agent (C).
The acrylic copolymer (A) is a copolymer of a monomer mixture containing the following monomers (a-1) to (a-3).
The monomer (a-1) is contained in an amount of 10 to 50% by mass, the monomer (a-2) is contained in an amount of 40 to 80% by mass, and the monomer (a-3) is contained in an amount of 5 to 10% by mass in 100% by mass of the monomer mixture.
The epoxy resin (B) is a bisphenol type epoxy resin having a weight average molecular weight (Mw) of 200 to 1000, and is a pressure-sensitive adhesive composition.

(A-1) A (meth) acrylic acid alkyl ester monomer having an alkyl group having 8 to 12 carbon atoms (a-2) A (meth) acrylic acid ester monomer having a glass transition temperature of 0 to 100 ° C. for a homopolymer (however, however) Excluding monomers (a-1) and (a-3))
(A-3) (Meth) acrylic acid alkyl ester monomer having a carboxyl group The pressure-sensitive adhesive composition according to claim 1, wherein the content of the epoxy resin (B) is 5 to 45 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the curing agent (C) contains an isocyanate compound. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, further comprising a silane coupling agent (D). A pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 4. An optical pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 4.